In some fields of engineering there is a strong trend towards increasing the amount of parts made of composite materials, e.g. in the aeronautical field: wing skins, cover plates and sections of fuselage are parts that can be manufactured using composite materials.
The manufacturing processes for these parts basically comprise a stage of tape-laying, in which layers of a composite material such as prepreg, which is a mixture of fibre reinforcement and polymer matrix capable of storage, are placed in a suitably shaped mould/tool, and a stage of forming and curing.
The composite material may take various forms and in particular the form of a mesh. The composite material meshes are not placed randomly but are arranged in each area in a number and with an alignment of their fibre reinforcement, typically carbon fibre, determined according to the nature and magnitude of the forces that the part is going to withstand in each area. The difference in thickness between the different areas causes mesh fall-offs, which needs to be set up and represented in a mesh model.
The design of such parts is carried out by means of a complex process including stages of calculation, mesh model design and analysis of their producibility, with feedback loops when changes are made in any of these stages.
Specialist engineers in computing use computer programs to calculate the behaviour of the part under given loads, and design engineers use CAD systems for generating the mesh model, i.e. to define the location and contour of the component meshes of the laminate, based on the specifications of the laminate supplied by the calculation results.
Even with CAD system functionalities, the process of generating the aforementioned mesh models in CAD systems is a tedious proceeding involving a great deal of repetitive manual work, with the consequent risk of mistakes, especially in the case of bent parts where, with current tools, the solid model of the part is obtained from a 2D mesh model—corresponding to the flat laminate which has to be made by a process of forming and curing to obtain the final part—by means of a process in which the reference lines have to be bent on the flange surfaces, and the areas or plateaux of different thickness, both in the core and in the flanges, having to be manually distributed taking into account all the joins between plateaux and the bending radii, this process being tedious, long and repetitive.
The impossibility of automatically or semi-automatically obtaining the solid model of bent parts of composite materials with the currently available CAD systems from the 2D mesh model of the flat laminate which is obtained in the first stage of manufacture of the said parts, is a drawback that hinders the design processes for such parts.
The present invention is aimed at solving this drawback.